1type: trigger
2name: sigmahq/proc_creation_win_susp_powershell_execution_via_dll
3description: |
4  Detects potential PowerShell execution from a DLL instead of the usual PowerShell process as seen used in PowerShdll. This detection assumes that PowerShell commands are passed via the CommandLine. 
5filter: |
6  (evt.Meta.service == 'sysmon' && evt.Parsed.EventID == '1') && ((evt.Parsed.Image endsWith '\\InstallUtil.exe' || evt.Parsed.Image endsWith '\\RegAsm.exe' || evt.Parsed.Image endsWith '\\RegSvcs.exe' || evt.Parsed.Image endsWith '\\regsvr32.exe' || evt.Parsed.Image endsWith '\\rundll32.exe' || evt.Parsed.OriginalFileName in ['InstallUtil.exe', 'RegAsm.exe', 'RegSvcs.exe', 'REGSVR32.EXE', 'RUNDLL32.EXE']) && (evt.Parsed.CommandLine contains 'Default.GetString' || evt.Parsed.CommandLine contains 'DownloadString' || evt.Parsed.CommandLine contains 'FromBase64String' || evt.Parsed.CommandLine contains 'ICM ' || evt.Parsed.CommandLine contains 'IEX ' || evt.Parsed.CommandLine contains 'Invoke-Command' || evt.Parsed.CommandLine contains 'Invoke-Expression'))
7blackhole: 2m
8#status: test
9labels:
10  service: windows
11  confidence: 1
12  spoofable: 0
13  classification:
14   - attack.t1218.011
15
16  label: "Potential PowerShell Execution Via DLL"
17  behavior : "windows:audit"
18  remediation: false
19
20scope:
21  type: ParentProcessId
22  expression: evt.Parsed.ParentProcessId
23
24